Physical and Electrical Properties of Atomic-Layer-Deposited Hf[sub x]Zr[sub 1−x]O[sub 2] with TEMAHf, TEMAZr, and Ozone

Abstract

In this work, physical and electrical characteristics of atomic-layer-deposited HfxZr1−xnormalO2 formed using tetrakis-ethyl methylaminohafnium (TEMAHf), tetrakis-ethylmethylaminozirconium (TEMAZr), and ozone are reported. Confirming Zr addition, film densities decrease with increasing Zr content. A slight increase in interfacial layer thickness is observed for ZrO2 after high-temperature annealing. All films remain smooth and void-free after high-temperature annealing. Tetragonal phase stabilization is observed with increasing Zr content. Carbon impurities are low and independent of Zr content. HfxZr1−xnormalO2 transistors and capacitors are fabricated for electrical characterization. Well-behaved capacitance–voltage characteristics are observed for all devices. Only a slight increase in gate leakage current is observed as Zr content is increased from <2% (HfO2) to ∼50% (Hf0.5Zr0.5normalO2) . HfxZr1−xnormalO2 devices have ∼50mV lower threshold voltage than HfO2 devices. High field mobilities of HfxZr1−xnormalO2 devices with 50 and 60% Zr content are higher than HfO2 or ZrO2 . All these results indicate HfxZr1−xnormalO2 is a promising dielectric for SiO2 replacement.

Influence of Oxygen Content on the Structure and Reliability of Ferroelectric HfxZr1–xO2 Layers

“…The difference between these two deposition techniques could depend on the chemistry of the deposited films. While PVD layers are deposited from HfO 2 targets having a purity of 99.9%, ALD layers are deposited from organic precursors whose byproducts cannot be completely removed during the purge steps of the deposition process. , As reported in Figure a, ToF-SIMS measurements show higher carbon contents in ALD-deposited films in comparison with PVD-deposited films. As reported in Figure b, C and CN impurities are distributed throughout the ALD-deposited films, with a slightly higher amount at the interface to the bottom electrode.…”

Sub-0.5 nm Equivalent Oxide Thickness Scaling for Si-Doped Zr1–xHfxO2 Thin Film without Using Noble Metal Electrode

“…Much research has been focused on obtaining a high dielectric constant by stabilizing the tetragonal structure ZrO 2 or HfO 2 by doping, e.g., Si doping of HfO 2 , Er doping of HfO 2 , and Y doping of ZrO 2 , − and Park et al reported remarkable enhancement of dielectric constant (∼47) by Al doping in relatively thick HfO 2 film . Although, there are some previous reports on undoped − or nanocrystal embedded Zr–Hf-mixed oxides − for gate dielectric, the research about combinations of Zr and Hf oxides in ternary metal oxide systems, which include matrices of ZrHf-mixed oxide and stabilizer dopant, for DRAM capacitor have rarely been reported.…”

Development of ALD HfZrO[sub x] with TDEAH/TDEAZ and H[sub 2]O

“…The ALD process window is at a lower temperature for the TDEA based process compared to the halide/H 2 O based or TEMA/O 3 based processes. 5,[20][21][22] This is mainly due to the lower decomposition temperature of the TDEA precursors compared to the halide precursors 24 as well as the different reaction regime between the O 3 and H 2 O based processes. 25 Related to a lower C content, the ALD temperature window should be at a higher temperature for metal-organic based processes.…”

“…These results confirm that adding Zr into HfO 2 helps to stabilize the tetragonal phase. 21,22 For HfZrO x films, the tetragonal phase usually has a higher k value than the monoclinic phase. 17,18 A higher k value benefits sub-nm EOT scaling further.…”

“…21͒ and metal-organic precursors tetrakisethylmethylamino ͑TEMA͒ hafnium/zirconium ͑TEMAH/TEMAZ͒ with O 3 . 22 The ALD HfZrO x films prepared by these different processes exhibit comparable physical and electrical properties. However, there are some limitations related to the abovementioned ALD HfZrO x processes: the halide based ALD processes show a significant growth incubation on hydrofluoric acid ͑HF͒-last ͑H-terminated͒ surfaces.…”